Conventionally, various types of dehumidifiers are known as a dehumidifier provided with an adsorption column allowing a to-be-treated gas to circulate therethrough so as to allow moisture in the to-be-treated gas to be adsorbed therein. For example, there is known a dehumidifier provided with an adsorption column including an adsorbent that adsorbs moisture, a column body that has a housing region containing the adsorbent, and a heating unit that is arranged within the column body and heats the adsorbent so as to cause desorption of the adsorbed moisture therefrom, see JP 2004-149890 A.
Such a dehumidifier includes a plurality of adsorption columns, specifically two adsorption columns, which are configured so that moisture in the to-be-treated gas can be alternately adsorbed therein. That is, this dehumidifier has a configuration such that, while moisture in the to-be-treated gas is adsorbed in one adsorption column, moisture is desorbed from an adsorbent in the other adsorption column so that the adsorbent is regenerated. More specifically, this dehumidifier has a configuration such that, while moisture in the to-be-treated gas is adsorbed in one adsorption column, a heating unit heats an adsorbent that has adsorbed moisture so as to cause desorption of the moisture from the adsorbent, followed by cooling the adsorbent, in the other adsorption column.